What has been dubbed "America's deadliest drug" has been found on the streets of Houston, according to city leaders.

Officials said Tuesday that officers recently found 80 grams of a substance that they thought was methamphetamine and sent it to a lab for testing. Those tests revealed that the substance that was found was actually a powerful opioid called carfentanil. Typically used to sedate elephants, carfentanil is 100 times more powerful than fentanyl and 10,000 times more potent than morphine. It was first manufactured in the 1970s. Doctors said that the tranquilizer dangerously lowers a person’s heart and breathing rates.

In its powdered form, carfentanil looks similar to table salt. Officials said ingesting a single grain of the drug can be fatal. Authorities said drug dealers are using the drug to cut their supply of opioids, like heroin, because it is cheaper. They said it has also been added to counterfeit pain medication by traffickers.

Governors and House leaders from across the country have formed a drug addiction task force and have vowed to fight the problem. On June 7, Houston Police confiscated a small amount of carfentanil and forensic specialists said it was enough for 4,000 lethal doses.

Mayor Sylvester Turner said the drug is here to stay, unless we do something about it.

"Leave these opioids alone, stay away from them and stay away from people who are using them," Turner said.

His warning comes with extreme urgency, since the smallest lethal dose might even be invisible.

"Twenty micrograms is what we think is the lethal dose, which is tiny, it's less than a grain of salt," said Dr. Peter Stout, president of Houston Forensic Science.